Enhanced engine controls have provided increased functionality as emissions and performance demands have increased. For example, electrically controlled throttles have improved vehicle drivability and improved engine emissions via adjusting a position of an engine throttle so as to adjust air flow to the engine so that fuel delivery can be matched more closely to air delivery to engine cylinders. However, electrically controlled throttles may receive torque demands from several inputs including from an operator of a vehicle. Further, the controls that adjust the throttle position may also receive other inputs that may have requirements that may be inconsistent or different from the inputs that contribute to the determination of throttle position. For example, some operators may choose to operate a vehicle using both of their feet. In particular, some operators may simultaneously depress an accelerator and a vehicle brake actuator to control vehicle speed through a corner or curve. Consequently, the vehicle controller may simultaneously receive inputs to accelerate and decelerate the vehicle. Driving a vehicle via simultaneously commanding the vehicle to accelerate and decelerate may make it more difficult to ensure that the operator has a desired level of control to accelerate and decelerate the vehicle. Specifically, it may be challenging to provide vacuum to actuate vehicle brakes to decelerate the vehicle as well as to provide engine torque to smoothly accelerate the vehicle after the vehicle brakes are at least partially released.
The inventors herein have recognized the above-mentioned limitations and have developed a method for operating an engine, comprising: reducing a desired engine torque in response to application of a vehicle brake during a condition where a requested engine torque is greater than a threshold level; and adjusting a rate the desired engine torque is increased after the vehicle brake is released in response to an operating condition while the requested engine torque is substantially constant.
By reducing engine torque during application of a vehicle brake, engine intake manifold pressure may be lowered so as to provide braking assistance to an operator such that vehicle braking force may be increased even though torque may still be output from the engine. In addition, by adjusting the rate of engine torque increase while the requested engine torque is substantially constant, vehicle acceleration may be controlled so as to provide smooth and predictable vehicle acceleration after braking.
The present description may provide several advantages. For example, the approach may provide improved braking assistance to a driver. Further, the approach can improve vehicle acceleration after vehicle brakes are released. Further still, the approach can prioritize vehicle acceleration and deceleration requests from an operator.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.